The invention relates to a circuit arrangement for preventing feedback on devices, each provided with at least one microphone and a loudspeaker. The invention is, in particular, suitable for loudspeaker installations and so-called "free-speakers" or "hands free telephones". Instead of this, it can also be employed for power amplifiers and the like.
Everywhere where, due to sound transmission, times occur, such as, for example, in the case of loudspeaker installations wherein the microphone takes up the dying-away sound of the loudspeaker, there are frequently acoustic feedbacks and feedback whistle of the installation. Such feedbacks are extremely disturbing and should as far as possible be eliminated without this causing disadvantages to the user. For this it is known to so down regulate the amplifier that the feedbacks are avoided. This causes, however, detrimental influencing of the capacity which per se is possible. Additionally, manual control is necessary.